Performance Tuning and Real-Time Behaviour

10 Lektionen in dieser Stufe

1. Profiling CPU, Memory and I/O Before Tuning
   Locate the real bottleneck with system and Python profilers. · Lab: Profile the Level 22 vision loop with cProfile and system tools and rank the three hottest spots.
2. Throttling, Temperature and Under-Voltage Flags
   Read firmware status bits and understand what they did to your performance. · Lab: Decode vcgencmd get_throttled during a stress test with good and poor power supplies.
3. CPU Governors, Overclocking and Its Risks
   Change frequency scaling and judge stability and heat. · Lab: Compare governors on a benchmark, then test a modest overclock with a soak test.
4. Memory Pressure, Swap and zram
   Keep a small-memory board responsive without wearing out storage. · Lab: Fill memory on purpose and compare behaviour with disk swap and with zram.
5. Making Python Faster: NumPy, multiprocessing and Compiled Helpers
   Apply vectorisation, process pools and native code where they pay off. · Lab: Speed up a pixel loop three ways and record each gain.
6. Why Standard Linux Is Not Real-Time: Latency and Jitter
   Define latency, jitter and deadlines and where delays come from. · Lab: Toggle a pin every millisecond from Python and capture the timing spread.
7. Measuring Jitter with cyclictest and a Logic Analyzer
   Quantify worst-case latency under load. · Lab: Run cyclictest idle and under stress and build a latency histogram.
8. Real-Time Scheduling Classes and CPU Isolation
   Use SCHED_FIFO, memory locking and isolated cores. · Lab: Pin a loop to an isolated core at real-time priority and re-measure.
9. Running a PREEMPT_RT Kernel
   Install or build a fully preemptible kernel and verify the gain. · Lab: Boot a PREEMPT_RT kernel and repeat the cyclictest comparison.
10. Hardware PWM, Timestamped Edges and Offloading to a Pico
    Use hardware peripherals and co-processors when software timing cannot meet the deadline. · Lab: Compare software PWM, hardware PWM through an overlay and Pico-generated pulses for jitter.

Abschlussprojekt

A tuned control loop with a written timing budget: measured worst-case latency on a stock and a real-time kernel, and a justified decision on what stays on the Pi and what moves to a Pico.

Teile für diese Stufe

• 1 × Raspberry Pi 5 set from Level 1
• 1 × Active cooler
• 1 × USB logic analyzer 8-channel
• 1 × Raspberry Pi Pico with headers
• 1 × USB power meter (USB-C, PD capable)
• 1 × Breadboard and jumper wire set

In jeder Lektion legst du die passenden Teile direkt in den Warenkorb. Raspberry Pi →